nix-travis-ci

Bootstrap Nix support on Travis CI (a humble near-drop-in replacement for language: nix)

Status: I put a few weeks of work into this project because I felt bad about the prospect of Nix projects being stuck with the rotting language:nix support on travis-ci, and wanted to give them an exit-path (I reached this goal months ago). I also intended to roughly track changes in install-nix-action, so that it'd be easier to people to move between them. However, after Travis-CI's pricing update, I feel like I've mostly wasted this work. For the time being, I'm happy to keep up with PRs--but I'm not sure I'll do any new feature work myself here.

Quickstart

If all of the jobs you're running use Nix, these two lines are usually enough to add Nix support to your .travis.yml (they replace language: nix if it's already in your config):

version: ~> 1.0
import: nix-community/nix-travis-ci:nix.yml@main

If you have a job matrix with some jobs that need Nix, and others that don't, you can do something like this to install Nix just for the jobs that need it:

version: ~> 1.0
import: nix-community/nix-travis-ci:nix.yml@main

jobs:
  include:
    - name: build that needs nix
      <<: *use_nix

Note: the import key is a Travis CI beta feature called Build Config Imports enabled by specifying version: ~> 1.0, and @main indicates the main branch.

Why not just use language: nix?

The community has trouble maintaining high-quality support for language: nix on Travis CI, so this project is intended to replace it.

How is this better than what it replaces?

There are a lot of small reasons, but they boil down to: it's easier to work on, so it'll take less time and effort to maintain or even improve.

Customizing

My general intent is for this repo and https://github.com/cachix/install-nix-action to have the similar if not identical options (even if usage has to differ a little). You can see an example of how to customize each of the following in this project's own .travis.yml.

• Nix (by overriding NIX_URL; the list of old versions is at https://releases.nixos.org/?prefix=nix)
• Nixpkgs channel (disable with SKIP_ADDING_NIXPKGS_CHANNEL or override with NIX_PATH)
• nix.conf (append a file specified by EXTRA_NIX_CONFIG)

In addition to these common options, you can also specify a version of this repository by changing main in import: nix-community/nix-travis-ci:nix.yml@main to any ref/tag/branch, such as import: nix-community/nix-travis-ci:nix.yml@v1